You have a Microsoft Exchange Online tenant that uses a third-party email gateway device.
You discover that inbound email messages are delayed.
The gateway device receives the following error message when sending email to the tenant.
4.7.500 Server busy, please try again later.
You need to prevent inbound email delays.
What should you configure?
A. Organization Sharing
B. an MX record for the domain
C. a transport rule
D. a connector
